Please use this identifier to cite or link to this item: https://doi.org/10.1098/rsta.2012.0198
Title: Cationic-vacancy-induced room-temperature ferromagnetism in transparent, conducting anatase Ti 1-xTa xO 2 (x ∼0.05) thin films
Authors: Rusydi, A. 
Dhar, S. 
Roy Barman, A.
Ariando 
Qi, D.-C. 
Motapothula, M.
Yi, J.B. 
Santoso, I. 
Feng, Y.P. 
Yang, K.
Dai, Y.
Yakovlev, N.L.
Ding, J. 
Wee, A.T.S. 
Neuber, G.
Breese, M.B.H. 
Ruebhausen, M.
Hilgenkamp, H.
Venkatesan, T. 
Issue Date: 28-Oct-2012
Citation: Rusydi, A., Dhar, S., Roy Barman, A., Ariando, Qi, D.-C., Motapothula, M., Yi, J.B., Santoso, I., Feng, Y.P., Yang, K., Dai, Y., Yakovlev, N.L., Ding, J., Wee, A.T.S., Neuber, G., Breese, M.B.H., Ruebhausen, M., Hilgenkamp, H., Venkatesan, T. (2012-10-28). Cationic-vacancy-induced room-temperature ferromagnetism in transparent, conducting anatase Ti 1-xTa xO 2 (x ∼0.05) thin films. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 370 (1977) : 4927-4943. ScholarBank@NUS Repository. https://doi.org/10.1098/rsta.2012.0198
Abstract: We report room-temperature ferromagnetism (FM) in highly conducting, transparent anatase Ti 1-xTaxO 2 (x ∼0.05) thin films grown by pulsed laser deposition on LaAlO 3 substrates. Rutherford backscattering spectrometry (RBS), X-ray diffraction, protoninduced X-ray emission, X-ray absorption spectroscopy (XAS) and time-of-flight secondary-ion mass spectrometry indicated negligible magnetic contaminants in the films. The presence of FM with concomitant large carrier densities was determined by a combination of superconducting quantum interference device magnetometry, electrical transport measurements, soft X-ray magnetic circular dichroism (SXMCD), XAS and optical magnetic circular dichroism, and was supported by first-principles calculations. SXMCD and XAS measurements revealed a 90 per cent contribution to FM from the Ti ions, and a 10 per cent contribution from the O ions. RBS/channelling measurements show complete Ta substitution in the Ti sites, though carrier activation was only 50 per cent at 5 per cent Ta concentration, implying compensation by cationic defects. The role of the Ti vacancy (V Ti) and Ti 3+ was studied via XAS and X-ray photoemission spectroscopy, respectively. It was found that, in films with strong FM, the V Ti signal was strong while the Ti 3+ signal was absent. We propose (in the absence of any obvious exchange mechanisms) that the localized magnetic moments, V Ti sites, are ferromagnetically ordered by itinerant carriers. Cationic-defect-induced magnetism is an alternative route to FM in wide-band-gap semiconducting oxides without any magnetic elements. © 2012 The Royal Society.
Source Title: Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
URI: http://scholarbank.nus.edu.sg/handle/10635/84430
ISSN: 1364503X
DOI: 10.1098/rsta.2012.0198
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